Since January 1998, the U.S. FDA has required enriched cereal grain products to be fortified with 140 mcg folic acid per 100 g. The purpose of this fortification was to reduce the incidence of neural tube defects by increasing the folic acid consumption of women of childbearing age. Our assessment of the impact of this fortification, using folate status based on changes in plasma and red blood cell folate levels in the Framingham Offspring Cohort Study, indicated a much greater impact on folate status than anticipated. Our hypothesis is that this higher impact of fortification on plasma folate levels is due to overages of folic acid fortification on enriched cereal grain product. The overall aim of this study is to determine the amount of folic acid and natural folates in nationally representative food samples of fortified cereal grain products, using the affinity/HPLC method, which allows these folates forms to be measured separately. It is necessary to distinguish between these two forms of folate in order to calculate total folate intake in individuals or populations as Dietary Folate Equivalents (DFE= mcg of natural folate + mcg of folic acid x 1.7). It is also very important to be able to quantify folic acid intake because the Tolerable Upper Intake Level and the recommendations for women of childbearing age are expressed for folic acid alone. The food samples that we will measure are part of the National Food and Nutrient Analysis Program (NFNAP). We will then apply this information on natural folate and folic acid content in fortified products to food frequency data collected as part of the Framingham Offspring Study to provide a measure of the actual increase in folic acid intake due to this fortification, the prevalence of individuals with adequate total folate intake and the prevalence of individuals with folic acid intakes above the Tolerable Upper Intake Levels. Our measurements of natural folate and folic acid in enriched cereal grain products will contribute to update future releases of the USDA nutrient databases. Folate status is thought to impact a number of diseases including neural tube defects, cardiovascular disease and colorectal cancer. In order to assess the impact of folic acid fortification, it is necessary to have valid data on the actual synthetic folic acid content of fortified foods.